Mast construction for lift trucks



Aug. 23, 1949. E. w. WEAVER IAST CONSTRUCTION FOR LIFT TRUCKS 3 Sheets-Sheet 1 Filed Sept. 25, 1947 INVEN TOR. 41 VERTON w WEA VB? OENE Y5 E- W. WEAVER MAST CONSTRUCTION FOR LIFT TRUCKS Aug. 23, 1949.

Filed Sept. 25, 1947 3 Sheets-Sheet 2 ILlIlllLl l l l l I k I l l l l I l INVENTOR. umro/v w W5 (/52 fig TM A f0e- 45 Aug. 23, 1949. E. w. WEAVER MAST CONSTRUCTION FOR LIFT TRUCKS Filed Sept; 25, 1947 I5 Sheets-Sheet 3 E w mm EW WW r I M W E f. w a a Patented Aug. 23, 1949 2,480,066 MAST CONSTRUCTION FOR LIFT TRUCKS Elverton W. Weaver, Cleveland, Ohio, designer to Towmotor Corporation, Cleveland, Ohio, a corporation of Ohio Application September 25, 1947, Serial No. 776,079

11 Claims.

been limited by the over-all height of the machine, as dictated by the height of doorways and similar overhead obstructions, the length of the arms or hangers for the load-supporting member, and the length of the portion of the slide which it retained in or by the mast when the slide is disposed in its distended position.

The primary object of this invention resides in the provision of a structure which will effectuate the elevation of the load-supportin member approximately double that of lift trucks of prior construction without increasing the over-all height of the machine.

Another object of the invention is to provide a platform-elevating mechanism which may be controlled by the operator in a manner similar to that heretofore employed in machines of like construction.

Another object of the invention is to provide a mast assembly which is designed to afford the operator a clear view through the mast assembly and a full unobstructed view around other portions of the vehicle.

Further objects of the invention reside in the provision of an elevating mechanism which is economic of manufacture, sturdy of structure, eflicient of operation, and free from any appendages of the character that tend to restrict the maneuverability of the vehicle.

Other objects and advantages more or less ancillary to the foregoing and the manner in which all the various objects are realized will appear in the following description, which, considered in connection with the accompanying drawings, sets forth the preferred embodiment of the invention.

Referring to the drawings:

Fig. 1 is a view in perspective of a vehicle of a well-known type embodying the improved mast assembly;

Fig. 2 is a similar view of the machine, illustrating one of the mast slides in its actuated position;

Fig. 3 is another perspective view of the machine illustrating the secondary mast and slide therefor in their elevated position;

Fig. 4 is a front elevational view of the improved mast assembly. portions thereof bein broken away in the interest of clarity;

Fig. 5 is a side elevetional view thereof Fig. 6 is a transverse section through the mast, the section being taken on a plane indicated by the line 6-6 in Fig. 5

Fig. 7 is a view in perspective of the secondary mast embodied in the improved elevating mechanism;

Fig. 8 is a transverse section through the mast. the section being taken on a plane indicated by the line 8-8 in Fig. 5; and

Fig. 9 is a vertical section through a portion of the slide roller supporting structure, the section being taken on a plane indicated by the line 9-9 in Fig. 8.

As illustrated in Figs. 1 to 3, the industrial truck comprises, generally, a body l0 mounted on a suitable chassis including the usual frame,

wheels H, a steering gear l2 in the forward end of th truck, and a valve control unit is adjacent the steering wheel which is coupled with a pump of conventional form driven by an engine (not shown) mounted in the body In. The forward end of the truck is provided with a first mast assembly H which embodies a pair of parallel channels ii iulcrumed for inclined adjustments at the base thereof upon a frame cross member l6 which is mounted on the body chassis. The lower ends of the channels are held in spaced relation by a plate H which further serves as the support for a vertical hydraulic lift cylinder l8. The free end of the piston rod IQ for the hydraulic cylinder is provided with a cross head 20 having idler rollers 2| thereon with chains 22 roved thereover. The ends of the chains are connected respectively to a fixed plate 23 on the first mast I5 and a bracket 24 forming part of a carriage assembly for a second, an outer mast 25 which is guided in a first or inner slide 26 embraced by the channels IS. The first slide 26 preferably comprises a rectangular frame formed of side rail channels 21 disposed in telescopic relation with the channels l5, which are united by top and bottom tie plates 28. The carriage assembly for the outer mast 25 includes bracket 24 constructed with laterally disposed plates 29 thereon which are fabricated for the support of rollers 30 designed for engagement with the flanged portions of the slide 26 and secondary rollers 3| engaged with the inner web of the slide channel. As will be seen in Figs. 8 and 9, the rollers 3| are supported by pins l3l mounted in bars I32 disposed within the channels 21 in paraliel relation thereto. The bars are supported by cap screws I33 mounted in the plates 23 and may be adjusted laterally to attain the requisite clearance between the rollers and the channels by manipulation of the screws I33 and set screws I34 disposed in tapped Openings in the plates 29 for abutting engagement with the end portions of the bars.

The second or outer meet 2! is formed with a transverse frame member 32 having a vertically disposed second cylinder 33. thereon similar in structure to the mast N. The piston rod 34 for the second cylinder 33 is provided with a cross head 35 carrying idler rollers II which guide chains 31 connected to a frame cross member II and to a slide 38 telescopically engaged with the channel irons of the outer mast N. The second or outer slide 39 is provided with a cross member 40 designed for the support of the load-carrying platform shown in the present embodiment as forks 4|. 42 carrying rollers 43 engaged with the flanged portions of the slide channels. The upper end of the slide 33 is framed with a cross member 44 disposed in spaced relation with the cross head 35 when the second piston is in its retracted position, and abutting engagement therewith after the piston has traveled approximately twelve inches during the ascent thereof. The second cylinder 33 is coupled with the source of fluid under pressure through a valve element in the control unit l3 operatively connected with a lever 45. Actuation of the lever 45 will permit the passage of fluid into the base of the cylinder and thus cause the'distention of the piston rod. 34 and the initial movement of the cross head. such movement will elevate the load-carrying platform 4| at twice the speed of the piston through the medium of the chains 31 until the cross head is brought into abutting engagement with the cross member 44 whereupon the second slide 33 will be lifted directly by the piston rod throughout the remainder of the stroke thereof. As the second slide ascends the load-carrying platform continues to be' lifted therealong to the position in the valve unit it may be operated to admit fluid into the base of the first cylinder l8 and thus effect the distention of the piston rod IS. The cross head in this assembly is engaged with the top cross member or cap 4! on the inner slide 26, hence movement of the piston for the inner mast will cause the elevation of slide 26. Since the chains 22 on the inner slide are coupled with the bracket 24 on the first or outer mast 25, movement of the cross head and slide 26 will effect the simultaneous elevation of the outer frame of the mast 25 together with its slide 39 and the load-carrying platform 4|.

The fluid connection between the valve and cylinder 33 in the outer mast assembly comprises a flexible tube preferably supported by one of the chains 22 for rimning movement therewith so that the hydraulic circuit may be maintained when the outer mast is elevated.

The return movement of the slides may be effected in the manner customarily employed in machines of this type, which, in brief, comprises manipulation of the valves in the control unit to cause the fluid in the cylinders to drain back through the supply lines to a reservoir, thus permitting the descent of the piston by gravity.

The slide 39 is formed with brackets If desired, however. the cylinders may be provided with conduits carrying motive fluid to both ends thereof in order to eflect the positive displacement of thepistons, 5 It will be readily recognized from the foregoing that the improved. elevating mechanism may be employed in such environs and for such elevational operations as single-masted vehicles heretofore constructed. but when greater elevational demands are encountered the utility of the machine may be increased by operation of the secondary mast which bodily lifts the primary mast assembly to a maximum height determined by the sum of the ascent of the slides in the two masts. It will be further recognized that although the extended height of the elevating mechanism is substantially double that of a single-masted machine, the retracted height thereof may be confined to facilitate the passage of the machine through doorways and like obstructions.

The control mechanism for each lift cylinder is the same as that heretofore employed in machines of similar character; hence. the flight of the slides for either or both of the masts may be arrested at any point during the translation thereof, and the load-marrying platform brought to rest at any altitude by the operation of either or both of the control valves. If desired, the cylinders 33 and i8 may be interconnected by a conduit arranged to effect the operation of the piston in the cylinder 13 after the piston in the cylinder 33 has reached its distended position. In such installation the two hydraulic lifts may be controiledfrom a single valve which is operated by the lever 45.

Although the foregoing description is necessarily of a detailed character, in order that the invention maybe completely set forth, it is to be understood that the specific terminology is not intended to be restrictive or confining, and that various rearrangements of parts and modifications of'detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. An industrial truck comprising a body, a mast on the forward end thereof, a slide thereon, a hydraulic lift for elevating said slide, a second mast carried by said slide and movable therewith, a slide thereon, a hydraulic lift for elevating said slide, a load-supporting platform carried by the last-named slide, a fluid connection between the two hydraulic lifts, means for operating the first-named lift upon completion of the operation of the second-named lift, and a valve for the control of the last-named lift.

2. An industrial truck comprising a body, a tandem mast structure pivotally mounted on the w forward end thereof, guideways in the masts, traveling members in the guideways, a hydraulic lift on each mast for actuating the traveling members, the outer mast being supported by the traveling member in the inner mast, and a loadsupporting fork supported by the traveling member in the outer mast.

'3. In a lift truck embodying a body, a pair of channels constituting a mast on the forward end thereof, a slide in the mast channels, a loadcarrying member associated therewith and a hydraulic lift for elevating the slide, means for regulating the running clearance between the slide and the load-carrying member, comprising bars disposed in the slide; means on the load-carrying 75 member for the retention and lateral adjustment load-carrying member threaded into said bars for lateral adjustment thereof,- set screws abutting said bars supported by the load-carrying member, rollers on said barsengaged -.with the webs of said slide channels; and rollers on said loadcarrying member engaged with thefianged portions of said slide channels.

5. In a lift truck,a chassis, a first mast mounted on said chassis, a first slide slidable along said first mast, a second mast slidably mounted on said first slide, first hydraulic lift piston and cylinder elements one of which is supported by said chassis, means connecting the other of said elements to said second mast to raise the same, a second slide slidably mounted on said second mast, a'

' load'carrying platform slidably mounted on said 7 if second slide, second hydraulic lift piston and cylinder elements, one of said second elements being supported by said second mast, and means con.- necting the other of said elements to said loadsupporting platform to elevate the same relative to said masts and slides.

6. In a lift truck, a chassis, a first mast mounted on said chassis, a first slide slidable along said first mast, carriage means slidably mounted on said first slide, a second mast supp rted by said carriage-means in front of and parallel to said first mast, first hydraulic lift piston and cylinder elements one of which is supported by said chassis, means connecting the other of said elements to said carriage means to raise the same together with said second -mast, a second slide slidably mounted on said second mast, a load carrying platform slidably mounted on said second slide, second hydraulic lift piston and cylinder elements, one of said second elements being supported by said second mast, and means connecting the other of said elements to said load-supporting platform to elevate the same relative to said masts and slides. a

, 'I. In a lift truck, a chassis, a first mast mounted on said chassis, a first slide slidable along said first mast, a second mast slidably mounted on said first slide, first hydraulic lift piston and cylinder elements one of which is supported by said chassis, means connecting the other of said elements to said second mast to raise the same, hydraulic means for controlling the relative extension of said first piston and cylinder elements, a second slide slidably mounted on said second mast,-a load carrying platform slidably mounted on said second slide, second hydraulic lift piston and cylinder elements, one of said second elements being supported by said second mast, means connecting the other of said elements to said load-supporting platform to elevate the same relative to said masts and slides, and hydraulic means for controlling the relative extension of said second piston and cylinder elements independently of said first elements.

8. In a lift truck, a chassis. a first mast mounted on said chassis, a first slide slidable along said first mast, carriage means slidably mounted on said first slide, a second mast substantially equal in height to said first mast and supported by said carriage means in front of and parallel to said first mast, first hydraulic lift piston and cylinder 6 elements one of which is supported by said chassis, means connecting the other of said elements to said carriage means to raise the same together with said second mast, a second slide slidably mounted on said second mast, a load carrying platform slidably ounted on said second slide, second hydraulic ig tpiston and cylinder elements one of said secon elements being supported by said second mast, and means connecting the other of said elements to said load-supporting platform to elevate the same from a position adjacent the bottom of said second mast to a position near the top of said second slide.

9. In a lift truck, a chassis, a first mast mounted on said chassis, a first slide slidable along said first mast, a second mast slidably mounted on said first slide, first hydraulic lift piston and cylinder elements one of which is supported by said chassis, means connecting the other of said elements to said second mast to raise the same, a second slide slidably mounted on said second mast, a load-carrying platform slidably mounted piston and cylinder elements one of which is sup-' ported by said chassis, a crosshead and roller on the other of said elements, a chain connected at one end to said first mast and at the other end to said first slide and rove over said crosshead roller between said points 'of connection to raise said first slide and second mast upon actuation of said first piston and cylinder elements, a second slide slidably mounted on said second mast, a load-carrying platform slidably mounted on said second slide. second hydraulic lift piston and cylinder elements, one of said second elements being supported by said second mast, a crosshead and roller on the other .of said elements, and a chain connected at one endto said second mast and at the other end to said load-supporting platform and rove over said last-named crosshead roller between said points of connection to raise said platform relative to said slides and masts.

11. In an industrial truck, a chassis, a first hydraulic lift comprising a mast supported on said chassis, supporting means associated with said mast, and a hydraulic motor for elevating said supporting means relative .to said mast, a second hydraulic lift comprising a mast supported by said supporting means, a load-supporting platform, and a second hydraulic motor for elevating said platform relative to said second mast.

ELVERTON W. WEAVER.

REFERENCES CITED The following references are of record in the file of this patent:

Johnson Sept. 30, 1947 Disclaimer 2,480,066.-E'lvr0n W. Weaver Cleveland, Ohio. MAO! Commune-non IOR Lxn- Tnucxs. Patent dm Aug. 23, 1949. Disclaimer filed Mar. 10, 1950, by the aasignoe, Towmotor C Hmb enters this disclaimer to claims 2 and 11 of aid patent. I Gaul! April 11, 1.960.] 

